1. Field of the Invention
The field of the invention relates to semiconductor data handling devices and in particular, ways of reducing the power consumption of such devices.
2. Description of the Prior Art
There is an ever increasing desire to reduce the power consumption of semiconductor devices and to increase their performance. In order to provide high performance, threshold voltages have been scaled down as a lower threshold voltage allows a device to react more quickly. However, lower threshold voltages also result in higher leakage currents. In some devices such as memory this sub-threshold leakage dominates overall power consumption of the memory.
In order to reduce power consumption it is known to power gate devices, such that switching devices, either headers or footers are added to isolate a circuit from a power rail when the circuit enters an inactive mode. These devices need to be large devices so that they do not impede current flow in operational mode. A problem with such a system is that these large devices provide a substantial time delay in both powering down and powering up of the circuit. Furthermore, the delay for powering up must be carefully managed to control the inrush current, this control may result in a further increase to the wakeup time.
It would be desirable to provide a semiconductor system with lower power consumption, while maintaining performance when required.